起伏地形清管过程中管内流动状态研究

Flow State of Natural Gas Pipeline Buried in the Undulating Terrain during Pigging

目的以中原丘陵地带某天然气管道清管过程为依据,针对起伏地形清管过程中的管内流动状态变化,明确天然气清管过程中的管内流型变化,并根据积液量提出清管时间。方法通过OLGA软件揭示清管过程中管内流动参数的变化过程,并提出相应的清管周期。结果清管器在上行过程中会导致入口处的压力和温度略有增大,而越过高点时,速度迅速增大,引起入口压力和温度迅速下降,当达到最低点时,清管器前积液量达到最大值。同时出口处出液速率与清管器运行时间呈幂指数增大,通过积分可得出总出液量为333 m3,与实际结果相吻合。对于天然气管线来说,对管内积液量影响最大的因素为气相流速,其次为起伏角度,最后为液相流速。结论由于清管后天然气稳定运行60天后管内积液量达到最大值,因此建议在20天积液量为100 m3时进行清管,同时设计末端容器体积裕量为1.2。

The work aims to clarify the change of flow pattern in the natural gas pigging process and propose the pigging time according to the amount of liquid accumulated based on the change of the flow state in the natural gas pipeline buried in the undulating terrain during pigging.The change process of the flow state parameters during pigging was revealed through OLGA software,and the corresponding pigging cycle was proposed.The pig running in the ascending pipe made the pressure and temperature at entrance increase slightly,while its velocity increased rapidly when the pig crossed the high point,causing the pressure and temperature at entrance to decrease rapidly.When the pig reached the lowest point,the amount of liquid accumulated in front of the pig was up to the peak.At the same time,the discharge rate of liquid at exit increased exponentially with the running time of the pig and the total volume of outflowing liquid was 333m3 through integral computation,which was consistent with the actual results.For natural gas pipelines,the gas phase flow rate,followed by undulation Angle and liquid phase flow rate,was the most important factor affecting the amount of liquid accumulated in the pipeline.The amount of accumulated liquid in the natural gas pipeline reaches the maximum after the stable operation of pigged natural gas for 60 days.Therefore,it is recommended to conduct pigging when the amount of accumulated liquid is 100m3 within 20 days,and the volume margin of the designed end container is 1.2.